June 21, 2012

WHY ClientAccessArray name is internal ONLY

When deploying E210 it is recommended to set CAS ARRAY. ( Client Access Server Array) CAS Array is recommended even you have one CAS or a single multi-role Exchange serves you have in your deployment plans.

I wanted to reiterate why the FQDN of CAS Array should be internally resolvable via internal DNS and should not be exposed to outside.

The short answer is to prevent delay on outlook clients when they are outside and trying to connect. now let’s look into this a bit deeper and try to understand what does this mean to us?

when client opens outlook internally, outlook will try to resolve the home server property configured within the outlook. So the outlook gets FQDN something like outlook.internal.local which then , Outlook checks its configured TCP/IP and finds out what DNS server to talk to and request IP address for the name outlook.internal.local ,

Outlook opens up internally by Client………

It resolves the “home server property” outlook.internal.local

It finds out what DNS server to talk too ( TCP/IP Stack defined on the workstation and DNS )

It will ask the IP Address of “outlook.internal.local “ ( We assume this was configured within outlook)